Improved dielectric permittivity and retained low loss in layer-structured films via controlling interfaces

The search for high-performance dielectric materials has long been driven by the urgent needs for various modern electronics. However, enhanced permittivity is always accompanied by elevated loss, which seriously hinders the development and applications of dielectric materials. Herein, negative-k layers were introduced into layer-structured films, forming a new class of multilayer composites consisting of alternately stacked positive-k and negative-k layers. Compared with traditional multilayer composites without negative-k layers, the layered composites containing extra positive-k/negative-k interfaces exhibit superior ability in balancing the contradict parameters: permittivity and loss, yielding substantially enhanced permittivity without sacrificing the low loss. It is indicated that the permittivity was enhanced by the charge accumulations and reinforced polarizations on the interfaces between positive-k and negative-k layers. Meanwhile, the loss induced by the leakage current was suppressed by the blocked transport of carriers between adjacent layers. The trilayered 60-3.5-60 composite exhibits an enhanced dielectric constant (epsilon' approximate to 33 @10 kHz) and retained low loss (tan delta approximate to 0.12 @10 kHz) compared with the single-layer BT/PVA composite containing 60 wt% BT fillers (epsilon' approximate to 9.5@10 kHz, tan delta approximate to 0.075@10 kHz). This research offers an effective way to design and fabricate novel high-performance dielectric materials.